While a variety of different fibers may be used in carrying out this invention, fibers of cellulosic material are stressed throughout this specification not only because of their suitability, but also because many are readily available from virgin or reclaimable sources and are relatively inexpensive. Wood fibers constitute an example of such a cellulosic material. These wood fibers, sometimes referred to as base fibers, are intertwined with and bonded to carrier fibers to create a moldable fibrous mat. The carrier fibers are adapted to melt under the heat and/or pressure of a subsequent operation in which the mat is molded into a product of predetermined shape.
Prior art in compressed wood fiber technology includes fiberboard, particle board and hardboard, terms applied to a variety of products made primarily from wood fibers, wood chips or shavings. These are not substantially formable. Extreme shapes, similar to those attainable through this invention, can be achieved by a so-called wet slurry process in which wood fibers are mixed with water and other chemicals and formed into a slurry which is applied over a pattern having the desired form. While satisfactory products can be made by the wet slurry process, it is a relatively expensive process not only in terms of the amount of energy required but also because of its long manufacturing cycle time and the cost of cleaning the effluent resulting from the process prior to dumping. This invention, however, relates to a dry process and product made therefrom.
It has also been known to form wood fiber based products by dry processing, but these previously known dry processes are capable of producing products having only relatively flat simple shapes.
It is a primary object of this invention to provide a unique dry process of forming a flexible mat consisting essentially of base and carrier fibers, the base fiber being a natural or synthetic fiber, and the carrier fiber being a linking fiber adapted to intertwine or interlock with the base fibers. The base and carrier fibers may be either virgin or reclaimed. Suitable base fibers are made of materials such, for example, as wood, jute, sisal, cotton, coconut, kapok, rayon, acetate, triacetate, paper, graphite, glass, mineral wool, and other synthetic and natural fibers. Products having far more difficult and complex shapes can be made from the material produced by this new dry process than could possibly be made by previously known dry processes. Material made by the method of this invention can be molded relatively fast and inexpensively into a variety of items such, for example, as decorative trim panels, automotive headliners, door panels, instrument panels, center trim pillars, package trays, consoles, furniture, luggage, building materials, packaging, automotive components, and the like. Such a product may have areas of differing density to provide portions that are soft to the touch or to provide visual embossing, and to provide both thermal and acoustical insulation. The ability to mold a self-supporting product with areas of low density eliminates the need for separate foam pads to be attached, thus offering significant economies.
A further object is to provide relatively flat, flexible, moldable fiber mat in continuous sheet or in sections from which products can be made; also to provide a method of making the mat into a final product and the end product itself.
In accordance with a specific embodiment of the invention, the mat may comprise a mixture of wood fibers and thermoplastic carrier fibers that mechanically intertwine or interlink with the wood fibers and are bonded or adhered to them to form interlocking connections which resist separation. The mat fibers are adhered together by heating the mat to a temperature and for a period of time such that the thermoplastic carrier fibers soften and become sufficiently tacky to heat-seal to the wood fibers and to each other, but still substantially retain their essentially fibrous form. The carrier fibers add substantial flexural strength to the mat so that even when products molded therefrom have complicated or difficult shapes and include sharp bends and cut-outs, the body of the mat will nevertheless hold together without ripping or tearing when the mold parts close. Other materials may be added to the formulation of the mat depending upon the characteristics desired in the finished product. As an example, a suitable thermosetting resin may be employed which will cure and set during molding to add structural stiffness and heat distortion resistance to the product.
A further object is to provide a process for molding the product described above and simultaneously molding and fusing a mounting bracket thereto, and the resulting end product.
These and other objects and features of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings.